US Bridges

Il 176 over Island Lake Overflow

Fair

McHenry County, Illinois · Island Lake · Structure no. 056003400000000

Built
1929
96 years old
Condition
Fair
inspected October 2023
Type
Slab
Concrete
Length
26 ft
1 main span
Daily traffic
19,200
2023 count
Owner
State
State Highway Agency

About this bridge

Il 176 over Island Lake Overflow is a concrete slab carrying Il 176 over Island Lake Overflow in McHenry County, Illinois. It was built in 1929, so it is 96 years old, older than the Illinois average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 19,200 vehicles a day, roughly 7% of them trucks, projected to reach 23,640 by 2046. The structure is 26 ft (7.9 m) long and 55 ft wide.

Location

Open in Google Maps
CarriesIl 176
CrossesIsland Lake Overflow
LocationIsland Lake
RouteState Highway 176
CountyMcHenry County
StateIllinois
Coordinates42.27538, -88.20253
Functional classUrban Other Principal Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating98.2 US tons
Inventory rating64.3 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length26 ft (7.9 m)
Longest span25 ft (7.6 m)
Deck width55 ft (16.9 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,200 (2023)
Projected traffic23,640 by 2046
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$288,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Il 176 over Island Lake Overflow built?

It was built in 1929, making it 96 years old in 2025.

What condition is Il 176 over Island Lake Overflow in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in October 2023.

How much traffic does Il 176 over Island Lake Overflow carry?

About 19,200 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is Il 176 over Island Lake Overflow?

The structure is 26 ft (7.9 m) long with a longest span of 25 ft (7.6 m) and a deck 55 ft wide.

Who owns Il 176 over Island Lake Overflow?

It is owned by the State Highway Agency.